Certified Crop Advisor Practice Exam

In a no-till system, comparing the top 2 inches of soil to soil below 2 inches, what is generally observed?

1. Lower soil test values

2. Higher soil test values

3. Equal soil test values

4. Less compaction

The correct answer is: Higher soil test values

In a no-till system, the practice involves leaving the soil undisturbed and not plowing it, which significantly influences soil properties. The upper layer of soil, particularly the top 2 inches, is often enriched with organic matter, nutrients, and microbial activity due to plant residues and minimal disturbance. This results in generally higher soil test values for nutrients like nitrogen, phosphorus, and potassium in the top layer compared to the soil that is deeper. The organic matter found in the surface layer plays a crucial role in nutrient cycling and retention, contributing to improved fertility levels. Microbial communities thrive in this environment, further enhancing the availability of essential nutrients. Conversely, the soil below 2 inches, while still viable, tends to be less influenced by these surface conditions, leading to comparatively lower nutrient concentrations. This phenomenon illustrates how the no-till approach can create a stratified soil profile, where the upper layers are more fertile and biologically active, a benefit for crop production.